It is known to remove limbs from trees by encircling the tree trunk or bole with curved cutting blades and either moving the curved blades along the length of the tree, or pulling the tree longitudinally through the curved blades. My prior U.S. Pat. Nos. 4,749,012, 4,899,794, and 5,515,895, each of which is incorporated in its entirety herein by reference, describe self-aligning cutter head assemblies for delimbing trees in which curved cutting and limb stripping levers having cutting blades are carried by a rectangular support frame supported for pivotal movement in both vertical and horizontal planes so that the limb stripping blades are automatically maintained in proper alignment with respect to the longitudinal axis of the tree as the tree is drawn longitudinally through the cutter head assembly in a generally horizontal orientation. A pair of curved limb stripping levers having curved cutting blades are spaced about the longitudinal axis of the cutter head assembly and are pivotable toward and away from each other for engaging and disengaging a tree bole. The limb stripping levers and blades are positioned and configured to substantially encircle a tree bole disposed in the cutter head assembly, except for the bottom portion of the tree bole for which a stationary blade is provided for removing limbs therefrom.
The delimbing devices disclosed in the aforementioned patents are relatively inexpensive to manufacture and maintain, and are highly effective and efficient for removing limbs from trees having a bole diameter of up to about 14 inches. However, in certain applications, trees having bole diameters of up to about 24 inches must be delimbed. For these larger trees, the curved limb stripping levers and cutting blades are not capable of encircling the uppermost portions of the tree bole and, consequently, limbs on these uppermost portions are not removed by the cutter head assembly.